But as John Sbardellati’s detailed retrospective on the period makes clear, the real driving force was actually the genuine – if totally unfounded – fear of FBI director J Edgar Hoover. Hoover’s concern? That communism was infecting the US way of life principally, it would seem, through ingeniously subtle propaganda inserted into Hollywood films.

There is much to dislike about Hoover and the book reveals him to be a paranoid, xenophobic, racist who moulded the FBI into a weapon to combat a cultural conspiracy which only existed in his mind.

J Edgar Hoover Goes To The Movies is not a work of character assasination though. It is a meticulous and objective look at how anti-communism took a firm hold of Hollywood.

As its author points out, Hoover’s fears reflected those of a country which never seems to stop labouring under the belief that its freedom is under threat. Hoover’s part was simply to heighten and spread the anti-communist fears already existing among conservatives in the post-war US.

Aided by organisations such as the Ayn Rand-supported Motion Picture Alliance and latterly the House Un-American Activities Committee, Hoover’s FBI mounted a mammoth secret investigation of the ideological content of Hollywood cinema.

Sbardellati reveals that Hoover’s delusional G-men began seeing the veiled spectre of communist ideology everywhere in films, from the positive depiction of a Russian soldier in the anti-fascist B-movie The Master Race (1944), to the demonisation of a capitalist banker in Frank Capra‘s now classic slice of Americana It’s A Wonderful Life (1946).

As it exposes the complex history of the time the book remains admirably succinct and focused. But Sbardellati’s new information also invites a new perspective. The human suffering of those blacklisted in the film industry, such as the Hollywood Ten, has been well documented but Sbardellati hints at a massive cultural loss as well.

As a climate of fear took hold and any film with even a vaguely liberal or politicised message became associated with the communist “threat,” Hollywood became afraid of producing films which examined or criticised US society.

Sbardellati’s book is fascinating and valuable because it gives us an insight into a point when US films began to ignore social problems.

Let’s not forget that a nation’s culture has a pronounced impact on its society. Hoover was right about that at least.